Lithium Recovery Device With Chloride-Deflecting Potential Gradient
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Solution Overview
Problem
Existing lithium recovery methods using electrodialysis face limitations in productivity due to chloride ions inhibiting lithium ion mobility, low concentration of lithium sources, and energy efficiency degradation, especially when recovering lithium from seawater or used lithium-ion batteries.
Innovation Solution
A lithium recovery device and method that includes a lithium ion-conducting electrolyte membrane with spaced apart electrodes and a sub-power supply to create a potential gradient, attracting chloride ions away from the membrane surface and enhancing lithium ion migration through electrostatic attraction, while maintaining a stable electric field to prevent electrolyte conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If voltage is increased to increase electron migration amount and Li+ mobility, then Li+ migration rate increases, but electrolyte membrane reaches potential causing metal ion reduction and electron conduction, stopping Li+ mobility improvement and deteriorating energy efficiency
Solution Approach 1:
The invention divides the single electrodialysis cell into two separate cells: a first cell for chloride ion removal and a second cell for lithium ion migration. This segmentation allows independent optimization of voltage application in each cell, preventing the electrolyte membrane from reaching reduction potential while maintaining effective lithium recovery.
Solution Approach 2:
The invention introduces an intermediate chamber between the first and second cells, filled with inert electrolyte solution. This intermediary chamber acts as a buffer zone that prevents direct electrical contact between the chloride-containing solution and the lithium recovery solution, while allowing independent voltage control in each cell.
2Productivity
If voltage is increased to improve Li+ mobility from low-concentration sources, then recovery rate increases, but chloride ions adsorb on electrolyte membrane surface inhibiting Li+ dissolution and migration
Solution Approach 1:
The invention separates the chloride removal process (first cell) from the lithium recovery process (second cell). By applying voltage independently in each cell, chloride ions are removed in the first cell without competing with lithium ions for membrane surface adsorption sites in the second cell.
Solution Approach 2:
The invention converts the harmful effect of chloride ions (adsorption inhibition) into a beneficial two-stage process: first removing chloride ions that would cause inhibition, then recovering lithium ions in a clean environment. The chloride removal stage transforms the problematic presence of chloride into an opportunity for selective pre-treatment.
3Productivity
If electrodes are placed in contact with electrolyte membrane to form electric field, then Li+ migration is enhanced, but electrode degradation occurs due to direct contact with chloride-containing solution
Solution Approach 1:
The invention places electrodes in contact with the electrolyte membrane only in the second cell where lithium recovery occurs, while the first cell handles chloride removal. This segmentation protects electrodes from direct exposure to high concentrations of chloride ions that would accelerate degradation.
Solution Approach 2:
The intermediate chamber filled with inert electrolyte solution acts as a protective barrier between the chloride-containing solution in the first cell and the electrodes in the second cell, preventing chloride-induced electrode degradation while maintaining system functionality.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method enables efficient recovery of lithium from low-concentration sources containing chloride ions, such as seawater, with improved productivity and energy efficiency by enhancing lithium ion mobility and reducing electrode degradation.
Implementation Method 1
a lithium ion-conducting electrolyte membrane that partitions the processing tank; Li+ contained in the electrolyte membrane 2 (electrolyte) is expressed as Li+ (electrolyte). This selectively moves Li+ from the Li-containing aqueous solution SW to the Li recovery aqueous solution RS
Implementation Method 2
The electrolyte membrane 2 does not allow metal ions Mn+ other than Li+ contained in the Li-containing aqueous solution SW, such as Na+ and Ca2+ with a larger diameter than Li+ to permeate therethrough, since the size of its lattice defect site is small
Implementation Method 3
By providing an electrode with a higher potential so as to be spaced apart from the electrolyte membrane in the Li-containing aqueous solution on the positive electrode side, chloride ions are attracted by electrostatic attraction near this electrode, reducing the concentration near the electrolyte membrane surface
Implementation Method 4
Voltage application by the power supply 151 causes the reaction of Formula (1) below near the electrode 131 in the Li-containing aqueous solution SW in the supply chamber 11, thus generating water (H2O) and oxygen (O2). When the Li-containing aqueous solution SW contains chloride ions (Cl−), the reaction of Formula (2) below occurs near the electrode 131, thus generating chlorine (Cl2)
Implementation Method 5
an electrochemical potential difference of Li+ contained in the Li-containing aqueous solution SW, the electrolyte membrane 2, and the Li recovery aqueous solution RS causes Li+ to permeate the electrolyte membrane 2 from the Li-containing aqueous solution SW and migrate into the Li recovery aqueous solution RS
Data Source
AI summary
This lithium recovery device 10C is provided with a processing tank 1 that is partitioned into a supply tank 11 and a recovery tank 13 by a lithium ion-conducting electrolyte membrane 2. In order to selectively move Li+ to an aqueous solution RS in the recovery tank 13 from an aqueous solution SW in the supply tank 11, the aqueous solution SW containing Li+ and other metal ions Mn+, this lithium recovery device 10C is also provided with: a first power supply 51 which is connected between a first electrode 31 that has a porous structure and is arranged so as to be in contact with a supply tank 11-side surface of the electrolyte membrane 2 and a second electrode 32A that is arranged within the recovery tank 13, in such a manner that the first electrode 31 functions as the positive electrode; and a sub power supply 53 which is connected in series to the positive electrode of the first power supply 51, while having the positive electrode thereof connected to a sub electrode 41 that is arranged within the supply tank 11 at a distance from the electrolyte membrane 2.